#include<bits/stdc++.h>
#define maxn 100005
using namespace std;
int n,L[maxn],R[maxn],ans,dp[maxn],maxx;
bitset<maxn>f;
signed main(){
    // freopen("lis.in","r",stdin);
	// freopen("lis.out","w",stdout);
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>n;for(int i=1;i<=n;++i)cin>>L[i]>>R[i];f[0]=1;
    for(int i=1;i<=n;++i){
        for(int j=R[i];j<=maxx;++j)if(f[j]){f[j]=0;break;}
        for(int j=R[i]-1;j>=L[i];--j)if(f[j])f[j+1]=1,f[j]=0;f[L[i]]=1;
        maxx=max(maxx,R[i]);
    }
    // for(int i=0;i<=n;++i)dp[i]=100001;dp[0]=0;
    // for(int i=1;i<=n;++i){
    //     int l=0,r=i-1,mid,st=-1;
    //     while(l<=r){
    //         mid=(l+r)>>1;
    //         if(dp[mid]<R[i])st=mid,l=mid+1;
    //         else r=mid-1;
    //     }
    //     for(int j=st;j>=0;--j)
    //         dp[j+1]=min(dp[j+1],max(dp[j]+1,L[i]));
    // }
    for(int i=1;i<=maxx;++i)if(f[i])ans++;
    cout<<ans;
	return 0;
}